The invention is directed to a method for the operation of a printing mechanism in an electrographic printer or copier, whereby a charge image is applied at the surface region of a toner image carrier. The surface region provided with the charge image is conveyed past the transfer surface of a transfer element at the spacing of a development gap, so that toner is transferred from the transfer surface to the surface of the toner image carrier.
The width of the developing gap is essentially determined by the spacing between toner image carrier and transfer surface of the transfer element. Different demands are made of the allowable width of the developing gap dependent on the printing or copying method employed. Applied, among other things, are electrophotographic methods, electromagnetic methods and inographic methods. Single-component and multi-component toners are employed as the toner. Liquid and solid toner are also distinguished.
In a known method, a relatively constant width of the developing gap is achieved in that the transfer surface is pressed against the surface of the toner image carrier by a pressing mechanism. The developing gap spacing can be prescribed via a spacer that, for example, rolls along on the toner image carrier with the assistance of rollers.
What is disadvantageous about this solution is that the rollers and the photoconductor as well are exposed to increased wear due to this type of spacing regulation. With increasing wear, however, the spacing is no longer held constant to the required extent.
DE 42 32 232 C2 discloses a method for setting the width of a developing gap, whereby an average gap width is set before the beginning of the printing process with a control circuit, without taking the radial deviation of a photoconductor drum into consideration. The radial deviation is then compensated during the printing process via a controller that employs a data bank having permanently prescribed data.